When Kim Jong Un prepares for his summit with President Trump it will be relatively easy for the North Korean leader to do homework on his rival.

He can start by reading The Art of the Deal, where the president describes his negotiating strategy and then turn to reviewing hundreds of tweets that reveal Trump's personality and, sometimes, his vulnerabilities.

But Trump’s advisers are having a harder time getting a read on the secretive Kim. Since assuming office, Kim has rarely left the country or met with foreign heads of state, except when he took a train recently to meet with Chinese President Xi Jinping.

“We have no data to evaluate him as a negotiator,” said Robert Einhorn, a former State Department official who met with Kim’s father as part of the Clinton administration negotiations with North Korea.

U.S. officials will get their first close look at Kim’s motives and negotiating positions during a meeting between Kim and South Korean President Moon Jae-in on Friday.

“It’s nice to have that kind of warm up,” said Gregory Treverton, chair of the National Intelligence Council in the Obama administration.

Analysts have concluded Kim has proven to be an adept negotiator. "He likes to take the initiative,” Einhorn said. “He likes to control the agenda and he likes to keep his adversaries off balance. Looked at from a professional point of view what he has been doing has been quite impressive.”

There is little in his background that would predict his success so far. Now in his early 30s, Kim was relatively unknown when he assumed power in 2011 after the death of his father.

He rarely leaves North Korea and has little exposure to life outside the isolated country, with the exception of several years he spent at a school in Switzerland. That makes it hard to predict how he will act when he sits down with Trump.

Still there are ways intelligence officials and diplomats can get a glimpse of Kim's strategic goals and tactics.

Kim’s pronouncements through the media are a form of negotiation, Einhorn said. Last year, Kim and his administration traded insults with Trump, calling him a “dotard” and launching a record number of ballistic missile tests.

His bellicose statements were designed to get the world to see North Korea as a world power. The missile testing allowed North Korea to expand its nuclear capabilities.

“Now he is prepared to pivot,” Einhorn said.

Last week he promised to suspend missile and weapons test and is planning to meet with Trump and Moon. The initiatives have been mostly Kim’s, though Moon’s invitation to attend the Winter Olympics in South Korea may have set the stage for some of the pronouncements from North Korea.

Trump agreed to meet with Kim without extracting any major concessions first.

“He’s played Trump very well,” Treverton said.

But Trump pushed back on that characterization at a press conference Tuesday, pointing out that economic sanctions against North Korea remain in place.

"A lot of concessions have already been made," Trump said. "We have made no concessions, despite some of the media saying that I’ve made concessions."

Trump has frequently boasted of his own negotiating skills. But some analysts worry that his confidence might lead Trump to underestimate Kim’s abilities.

“Almost every president thinks if you can just sit down with the other guy good things will happen,” he said. “That’s particularly true of Mr. Trump.”

Kim's reputation as a buffoonish leader with an odd haircut and mannerisms may contribute to that sense of confidence.

But analysts say the reputation has always been misleading. Kim is a cruel leader who rules with an iron fist, but he is not irrational.

Kim ordered his uncle, Jang Song Thaek, executed about a year after coming into power, according to the South Korean intelligence service.

More recently, he is suspected by South Korea's government of ordering the killing of his exiled half brother, Kim Jong Nam, a potential rival who was poisoned with a toxic nerve agent in Malaysia in February. Kim also executed five senior government officials with anti-aircraft guns, according to the South Korean government.

"He is ruthless but he's also been relatively strategic," Treverton said.